A model for contaminant mass flux in capped sediment under consolidation

The paper presents a model for contaminant transport and flux through a consolidating subaqueous sediment and overlying cap. The formulation is based on the effect of consolidation and excess pore pressure dissipation on transient, nonlinear advective component of transport through sediment and the cap. The consolidation is induced by the buoyant weight of the cap when it is placed on the contaminated sediments. One equation is presented for advective-diffusive transport through the sediment that is dependent upon soil/contaminant properties and transient advective velocity, which is calculated from a second equation based on the Terzaghi consolidation theory. A third equation is provided to describe the transport of contaminants in the cap. The parameters, including advective velocity, and boundary conditions used for contaminant transport through the cap are derived from the solution of the first two equations. The finite difference method is used to solve the system of equations for consolidation and contaminant transport. A hypothetical case is analyzed to demonstrate the formulation, and the results show that advection due to consolidation can accelerate breakthrough of contaminant through the cap by orders of magnitude. The derivation and results show that consolidation should be included for cap design, and that reactive caps are essential for delaying and reducing dissolved contaminant flux.     

Performance enhancement of a solar still using a V-groove solar air collector—experimental study with energy,exergy, enviroeconomic,and exergoeconomic analysis

Environmental Science and Pollution Research - This paper intended to evaluate the performance of a new design of solar still integrated with a V-groove solar air collector. In this system, an air...     

Removal of hinosan from underground water using NH4Cl-modified activated carbon from rice husk

Environmental Science and Pollution Research - In the present study, NH4Cl-modified activated carbon was synthesized from rice husk and used as an adsorbent for removal of hinosan from underground...     

Prevalence of anaemia among children living in five communities in and near Karachi,Pakistan

The primary objectives of this research were to estimate the prevalence of anaemia and low haematocrit among preschool children living in Karachi. Through a geographically stratified design, 349 children aged 36–60 months were selected, from five communities in and near Karachi. Blood samples were drawn from children and a questionnaire was administered to evaluate various demographic and socioeconomic characteristics. Chi-square test and multiple logistic regression procedures were used to compare the prevalence of anaemia and low haematocrit among various strata. The overall prevalence of anaemia and low haematocrit were 55.9 and 48.4%, respectively. Children living in the rural community had the highest prevalence of anaemia (78.7%) and low haematocrit (63.8%). Children aged 36–48 months had also higher prevalence of anaemia and low haematocrit. Children's nutritional status was significantly associated with both anaemia and low haematocrit. We recommend appropriate interventions to reduce the burden of these conditions in Pakistan.